This invention relates to an aircraft of the heavier-than-air type, and more particularly to a stability-enhancing feature for an aircraft.
Various structures are known for providing increased aircraft lift and/or stability. One such structure is shown in Kline et al., U.S. Pat. No. 4,046,338. This patent shows forming a step-like discontinuity in the lower surface of each aircraft wing and mounting a pivotal lift-generating member at the lower edge defined by the step-like discontinuity.
The present invention has as its object to enhance the stability and lift of an aircraft, constituting an improvement over the structure shown in the noted patent to Kline et al. It is a further object of the invention to provide such a structure which is easily incorporated into a small-scale or full-scale aircraft.
In accordance with one aspect of the invention, an aircraft includes upper and lower surfaces extending between a forward edge and a rear edge of the aircraft. The aircraft is substantially symmetrical about a longitudinal axis or centerline extending through the central portion of the aircraft. An upward step is formed in the lower surface of the aircraft forwardly of the rear edge of the aircraft. The upward step includes a rearwardly facing riser surface, with the step being located in the central portion of the aircraft. The aircraft upper and lower surfaces terminate in a pair of wing tips, and the rearwardly facing riser surface provided by the step terminates on each side of the aircraft well inwardly of the wing tip, so that a majority of the length of the lower surface of the aircraft on either side of the aircraft centerline is uninterrupted by the step. The rearwardly facing riser surface defined by the step is substantially vertical, and the portion of the aircraft lower surface disposed rearwardly of the step is substantially horizontal, extending between the rear edge of the aircraft and the upper end of the riser surface defined by the step.
In one form of the invention, the aircraft is adapted for manual launching by a user, and structure is provided on the lower surface of the aircraft extending rearwardly from the riser surface formed by the step, including a pair of side surfaces adapted to be engaged by the user's fingers.
The riser surface formed by the step tapers upwardly in a direction toward each wing tip, to merge with the uninterrupted lower surface of the aircraft.
In one form of the invention, the aircraft includes a central body portion extending along the aircraft centerline, with the step being formed in the underside of the body portion. The forward edge of the aircraft defines a forwardly extending central area to the body portion extending along the aircraft centerline, with the forward edge on either side of the body portion extending rearwardly and outwardly toward each wing tip and cooperating with the rear edge of the aircraft to define a pair of wings. The front-to-rear center of gravity of the aircraft is located approximately at the step. With this arrangement, the body portion located forwardly of the step provides a mass counterbalancing that of the wings and body portion located rearwardly of the step.
The invention further contemplates a method of enhancing the stability of an aircraft, substantially in accordance with the foregoing summary.
Various other objects, features and advantages of the invention will be made apparent upon consideration of the following description taken together the drawings.